The Manhattan Project

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Herbert Anderson's Interview (1965)

Herbert Anderson worked with Enrico Fermi on the Chicago Pile-1 at the Met Lab at the University of Chicago. He grew up during the Depression, accepting a scholarship to study electrical engineering before he transferred to physics. Anderson worked alongside Niels Bohr and Enrico Fermi at Columbia and helped run the night shift when physicists were putting together the CP-1.

Groueff: Terrific. You see, I have the details of the night of December 1st, and the day of December 2nd, as given by Dr. [Arthur] Compton and Mrs. [Laura] Fermi, etc. I talked to some of their colleagues there. I would like, if possible, for you to give me some details, a description of what you did the evening before, what time you went there and what stage the pile was at already.

Anderson: Let’s see, I was in charge of the night shift. We had a discussion with [Enrico] Fermi during the day about what we should do. We had already estimated, from the data of previous nights – I do not remember now exactly, but at the 51st layer, the pile would be in a critical condition.

Groueff: You already had 50 layers?

Anderson: I do not remember exactly how many now. We could usually put on some four or five layers a night. I cannot remember now how many. In this case, there were only three or four layers needed. We had agreed that when I reached the 51st layer – I do not recall the exact number, whether it was 51 or 53, something like that. We would go home. We would put in the cadmium rods and lock them.

Groueff: You would not start the reaction?

Anderson: That is right. We would make a measurement of the reactivity with one rod in. Then we would put all the rods in, lock them, and go home. We would not start the reaction until—

Groueff: In other words, you finished all the layers but you would not pull out the rod?

Anderson: We would not test it.

Groueff: You would not test it?

Anderson: We were asked by Fermi not to do that until he was there.

Groueff: What time did he leave and you took over, 4:00 in the afternoon or something like that?

Anderson: He was usually a person of very regular habits. He invariably went home at 6:00 or so.

Groueff: You remained alone? How many men, more or less, were with you?

Anderson: There was a crew. I do not remember how many there were, about eight or ten people who helped bring in the bricks and lay them down, and put them in place.

Groueff: Not scientists, just the helpers? A couple of scientists?

Anderson: I was the only senior scientist. We had a number of junior ones. I seem to recall David Hill, for example. He was a student type. We had a number of people who were really laborers, that did the heavier work.

Groueff: In other words, the day shift under Dr. [Walter] Zinn left?

Anderson: They left. I do not remember now the number, but something like the 48th layer was finished. A measurement was made. We went to discuss it with Fermi in his office.

Groueff: Zinn, Fermi, and you?

Anderson: Yes.

Groueff: They left, and you continued piling the other couple of layers?

Anderson: Yes, up to the 51st or 53rd. I do not remember.

Groueff: Do you remember what time of the night you reached this?

Anderson: I do not remember exactly. I think it was before midnight, 11:00 or something like that.

Groueff: You piled it personally? You helped with the bricks?

Anderson: Yes. I usually helped put things in place. The graphite slides very easily. You would just slide them across the top. Since there was no fixed design, I would decide how I wanted some of them placed.

Groueff: You were personally on top of the pile?

Anderson: Yes, always there, yes.

Groueff: When you finished the last layer, the 51st or whatever it was, what did you do? You went down to do some measurements?

Anderson: We had first the boron trifluoride counter, which one would measure with all the rods except one removed. Then we also measured with indium foils. Those were our standard measurements. They showed the predicted intensity.

Groueff: And the criticality was reached by then?

Anderson: No, it wasn’t reached because the rods were there.

Groueff: The number of bricks and uranium—

Anderson: It would be critical if the rods were removed.

Groueff: There you were, along with your crew, in the middle of the night. The only thing that was in the way to criticality was this rod?

Anderson: That is right.

Groueff: According to your instructions and agreement, you left.

Anderson: I realized that I could have had the honor of being the first one.

Groueff: It must have been a tremendous temptation for you.

Anderson: It was, but I did not take it too seriously.

Groueff: Why didn’t you do it, just to see, to peek?

Anderson: I had an agreement with Professor Fermi. He knew that I would be tempted. He made it.

Groueff: He knew that?

Anderson: Yes.

Groueff: You were one of his lieutenants, one of his closest—

Anderson: I was really quite loyal to him.

Groueff: You would not do it?

Anderson: I would not do it. I might think of it, but I would not do it.

Groueff: For a scientist, it must have been quite a temptation, to be first?

Anderson: On the other hand, I was willing to wait another day.

Groueff: You left and went to sleep?

Anderson: We had a procedure of putting in several more cadmium rods. They were catalogued so there would be no mistake. I sent everyone home and then went home myself.

Groueff: You came back the next morning, when the experiment—

Anderson: I came back the next morning and became an observer.

Groueff: You were on the balcony?

Anderson: Yes.

Groueff: Next to Fermi?

Anderson: Yes, I was right next to him.

Groueff: How old were you at that time, Dr. Anderson?

Anderson: I was younger than I am now.

Groueff: Twenty-three, or younger?

Anderson: Yes, and I am now fifty-one.

Groueff: You were quite young then. How did you happen to be so close to Fermi? You came from Columbia with him?

Anderson: I think that is all described in Mrs. Fermi’s book. I was a graduate student at Columbia. I was preparing some experiments for the cyclotron. In fact, I had helped build the cyclotron.

Groueff: The cyclotron at Columbia?

Anderson: At Columbia. We were building a cyclotron. I was a graduate student under [John] Dunning, who was the man in charge of the cyclotron. I worked on the construction of the machine, some of the design, and then the construction of the cyclotron. It was starting to work when Fermi arrived.

Not long after, in January of 1939, Professor [Niels] Bohr arrived with the news about fission. He arrived in New York and he came immediately to Columbia University, because he wanted to tell the news to Fermi. He did not find Fermi right away. He was looking for him and he found me instead. He was quite excited and he explained. He told everything to me.

Groueff: The first day he came to visit Columbia, you happened to be there?

Anderson: I happened to be there. He unburdened himself to me.

Groueff: You were just a young post-graduate student?

Anderson: I was just starting to do my doctoral research.

Groueff: It must have been a very exciting moment. Bohr was something like the Pope.

Anderson: Yes, that is true. It was very exciting. He finally found Fermi. Fermi had just arrived. He had no laboratory and no equipment. When I saw him, I proposed that since I had all of the equipment and I had built the cyclotron, that we should work together. He thought that was a very nice idea. It was arranged that way. We began to work together.

Groueff: You became very friendly, very close?

Anderson: Yes. We became very good friends. He was really my teacher at the time. We became quite close. We did work together ever since.

Groueff: When he moved from Columbia to Chicago in the beginning of 1942, you came with him?

Anderson: Yes. He was not too anxious to go, but in some ways I persuaded him that it would be a good idea.

Groueff: Why didn’t he want to go? He wanted to stay in New York?

Anderson: He wanted to stay in New York. He had just come and settled there. He was being treated very well. On the other hand, since he was an enemy alien, it was not possible for him to be in charge of such an important project. They were looking for an American scientist. The available American scientists who were interested were already deeply involved in other things. In the end, it was Compton who offered to take over the—

Groueff: Compton organized the Chicago build?

Anderson: Compton invited us all to come to Chicago, and then tried to persuade Fermi to come there. I remember Fermi mentioned it to me. Since I had not traveled very much, I was interested in the change. He was not. In any case, it was really Compton’s decision. At one point, he simply ordered everyone who wanted to keep working on that project to come to Chicago.

Groueff: You started since the beginning of this pile, the CP-1? You were on Fermi’s team since the beginning there?

Anderson: Oh yes, I was.

Groueff: Since the first brick, the first layer?

Anderson: That is right. In fact, Fermi and I, in a certain sense, brought the whole enterprise to Chicago, since it was in Columbia.

Groueff: At Columbia, you were already building some smaller piles?

Anderson: We were at that time, at the time that Compton took over. We were already building an intermediate pile.

Groueff: The so-called exponential?

Anderson: Yes, the exponential pile. What we did was put [Walter] Zinn in charge of that. He stayed in New York, while I came to Chicago to organize our work there.

Groueff: Zinn joined you later?

Anderson: When the exponential pile experiment was finished that summer at Columbia, then Zinn came to Chicago, too. Then we divided the work in Chicago between us.

Groueff: Zinn had one crew and you had another one?

Anderson: Yes. Zinn was really somewhat senior to me.

Groueff: He was an older man?

Anderson: He was an older man. He was the first lieutenant and I was the second lieutenant. He got the day shift.

Groueff: You had the night shift. You would usually work the whole night?

Anderson: Usually we worked a fixed number of layers, really. As I recall, we usually finished around 2:00 or 3:00 in the morning. We did not really work through the night. We worked from about 6:00 or so, or 8:00, I do not remember.

Groueff: Until 2:00?

Anderson: Until about 2:00, the normal, 2:00 or 3:00, was the normal shift, except on the final night. As I recall, we were through before midnight. I do not recall the exact time.

Groueff: You were the last one to leave the pile before the experiment?

Anderson: Yes. I was the last one to leave. I sent everybody home.

Groueff: You must have had quite a moment there, all alone in the night with the pile. Did you have some feelings of fear that some accident may happen the next day, or the pile would not work as predicted? You were pretty sure by then that it would work?

Anderson: There was always some question that you might have overlooked something. The pile behaved in every way, the way we had predicted. Fermi would plot. Every day we made a measurement. The measurements always went the way we thought they should.

Groueff: According to theory?

Anderson: Things looked extremely well-behaved. I think it is true that the pile is very unusual in that it is very rare that experiments are so completely understood. It does not frequently happen, that there are as few surprises as there were with that one.

Groueff: I understand Fermi was very comfortable that day. He was not overly excited. He did not show any fear.

Anderson: I really think that Fermi was going to make a good show of it. He was very much on stage and acting.

Groueff: He was a showman?

Anderson: He was very much the showman on that day. He wanted to impress everyone with the achievement, really. It was essentially to demonstrate how thoroughly he understood everything.

Groueff: It was a lot of showmanship in the sense that he could have done it quicker?

Anderson: It was very much showmanship. He had a lot of people watching. He was really showing his mastery of the whole thing.

Groueff: He enjoyed it?

Anderson: Oh, yes. He just enjoyed it tremendously.

Groueff: I understand he was trying to predict at each point what would happen exactly.

Anderson: He did that with great flourish, what would happen each time he pulled out the rod. He would show where the meters would go on the instruments. He would even mark them.

Groueff: Exactly what would happen?

Anderson: What would happen.

Groueff: It must have been very impressive to watch him, like a high priest appreciating an act. What was your role that day, personally? You were just a spectator?

Anderson: I was just standing next to him.

Groueff: Reading instruments?

Anderson: Verifying the things he was doing and so forth.

Groueff: It is good that he was handling the slide ruler all the time and calculating very quickly with his fingers.

Anderson: He had a little six-inch slide rule. He used it to calculate. He would record the data and then calculate where the next should be. He prepared himself quite well, you see, to know what to do with each new measurement. He had a chart already prepared, so that he knew pretty well.

Groueff: Everything happened exactly as he predicted it?

Anderson: That is right.

Groueff: Actually, during the experiment, the only active part was played by him and—

Anderson: One of my colleagues, who had a slightly more minor role. He was on the floor.

Groueff: Pulling out the rod?

Anderson: Pulling out the rod. He had designed the special safety rod, which he called the Zip.

Groueff: I think Dr. Zinn was in charge of that.

Anderson: He stood there in case anything bad happened. He would personally take the proper action.

Groueff: Dr. Hilberry with an axe.

Anderson: That was a joke. I think the serious safety was Zinn, who had designed a special safety device. He was there to see that it would work if needed.

Groueff: You did not have to work it, to use it?

Anderson: We always put that in anyway, at the very end.

Groueff: I understand that when the tension was mounting and it was getting very dramatic, Fermi suddenly turned and said, “Let’s go for lunch.” You all went to the cafeteria and came back in the afternoon, and continued?

Anderson: That is right. He had done the preliminary experiments in the morning, removing the cadmium rod a little bit of the time and noticing that the activity was increasing.

Groueff: The great show he wanted to start after lunch?

Anderson: Yes. He was very calm about everything. He had essentially prepared things very well, as he always did, so that he would be in a position to interpret what happened in the proper way.

Groueff: He was a very thorough man in his experiments?

Anderson: Oh, yes.

Groueff: Was George Weil a young man or old, tall or short? If I had to describe him?

Anderson: He is about ten years older than I am. He was about thirty-seven or so. I would describe him as 5’8” or so, and weighs 145 or something like that. He is a man of edium/slight build.

Groueff: Glasses? Did he wear glasses or anything?

Anderson: It is hard to know. I think he wears them now.

Groueff: Was he very nervous by doing all this?

Anderson: I would not say so. I do not think any of us were nervous, those of us who had worked with this a long time. In a sense, it was what we had been thinking about for several years.

Groueff: You knew that it was just a show at the end?

Anderson: It is never a show when it is the first time. It was the first time. I think we all have the feeling that we had everything under control. We knew extremely well what was going to happen. At least we thought we understood everything. As it turned out, we did. There were really no surprises at all, which is unusual.

I think it is typical in such enterprises that you try during the design and construction to understand everything as fully as you know how. Usually, you find that you missed something. In this case, every detail had been thought of, and considered and understood deeply by the few of us who were really involved.

I would say that Zinn, myself, George Weil and Fermi knew the particular thing extremely well. We had measured everything that went into it. We calculated its behavior. Fermi did it, but all of us did it too, independently, to make sure we knew what we were doing.

Groueff: Where do you come from, Dr. Anderson? Are you a New Yorker?

Anderson: Yes, I am a New Yorker by birth.

Groueff: You studied in New York?

Anderson: I took all my education in New York, in the public schools, then Stuyvesant High School in lower Manhattan. After that, I went to Columbia as an undergraduate, first as an engineering student. I studied electrical engineering. Then when I finished the course in electrical engineering – what happened is that those were the days of the Depression. There was something called the NYA, the National Youth Administration. That offered some part-time jobs to students. I took one that was to help one of the professors in the physics department.

Groueff: While you were studying electrical engineering?

Anderson: I was studying electrical engineering, but I had a part-time job in the physics department, with a man who is now a professor there, Mitchell. At one point, he suggested that I should study physics. I had not ever considered that before. I did not know that I was well suited. He looked at my grades and he discovered that I had quite a few As in physics. He arranged that I should get an assistantship. After I received my degree in electrical engineering—

Groueff: You finished your electrical engineering?

Anderson: Oh yes, I received an AB degree from the college, and then a BS degree in electrical engineering. Then I simply transferred to the physics department.

At that time, Dunning was starting the cyclotron. I helped with some of the radio engineering design. That was my specialty. I designed some new features of the radio frequency. When the cyclotron was finished, I planned to do my research with it. That was when Fermi came. I transferred.

Groueff: Your first knowledge about the nuclear thing came directly from Bohr?

Anderson: That is right.

Groueff: Just because he happened to walk in the lab while you were there?

Anderson: Yes, that is right.

Groueff: You met Fermi after that?

Anderson: I knew Fermi. I had been in one of his courses. He had just really arrived shortly. He was around in the lab, so to speak.

Groueff: He was working with Dunning and those people?

Anderson: Yes. The lab is a big place, in particular with the cyclotron. He visited when he came. I had a chance to meet him.

Groueff: Were you immediately impressed by him?

Anderson: He was quite famous. I had known of his work. Fermi was an expert on neutrons and Dunning was interested in neutrons. My research that I had planned to do was with neutrons.

Groueff: You wanted to discuss your work with him?

Anderson: I wanted to discuss my work in any case with Fermi. It seemed to me that what I had planned would be very uninteresting compared to what was now possible.

Groueff: It must have been tremendously exciting for a young man to be with the top people like Bohr and Fermi.

Anderson: The only thing is that the young man does not know what is exciting and what is not, until later. I thought that was what one should expect.

Groueff: You take it for granted. What family do you come from? Were you a well-off family?

Anderson: No, we were rather a poor family. I had a scholarship.

Groueff: The Lower East Side? What do they call it, Stuyvesant?

Anderson: No, I grew up in the Bronx. I went to Stuyvesant because it had a scientific – I was interested in an engineering career. Stuyvesant offered a special school. I had to travel about an hour and a half to go to school, on the elevated.

Groueff: From the Bronx?

Anderson: From the Bronx.

Groueff: In other words, you had to take the summer job. That is how you went into physics.

Anderson: It was not a summer job.

Groueff: It was a part-time job?

Anderson: It was the National Youth Administration part-time job, several hours a day, during the school.

Groueff: You had to do the two things together, the job and studying for your own exams?

Anderson: Yes, my courses. At that time, I was studying engineering already. There were several hours in the afternoon and evening that I would help in the lab as a physicist in the physics department.

Groueff: At that time, when you met Fermi and you started doing the experiment, were you the kind of young man with a lot of self-assurance? Were you on the shy and timid side?

Anderson: Me?

Groueff: You.

Anderson: I was never very shy.

Groueff: You were quite self-confident? You were not too impressed by a guy who had Nobel Prizes?Anderson: I was impressed, but I thought that these were the people I should work with.